Tobacco curing apparatus



Feb. 6,1968 COPELAND, JR 3,367,643

TOBACCO CURING APPARATUS Filed Nov. 23 1965 3 Sheets-Sheet 1 FIG. I

M) W Q ATTORNEY Feb. 6, 1968 w. c. COPELAND, JR

TOBACCO CURING APPARATUS Filed Ndv. 23, 1965 3 Sheets-Sheet z m M mm m m w w ql G Feb. 6, 1968 w; c. COPELAND, JR

TOBACCO CURING APPARATUS 3 Sheets-Sheet 5 Filed Nov. 23, 1965 INVENTOR. h alfer 6. 6 0410220; #7: BY

ATTORNEY United States Patent 3,367,643 TOBACCO CURING APPARATUS Walter C. Copeland, Jr., Madison, Fla. 32340 Filed Nov. 23, 1965, Ser. No. 509,383 7 Claims. (Cl. 263-19) ABSTRACT OF THE DISCLOSURE A gas-fired tobacco curing system for curing tobacco hung in a barn including a cylindrical combustion chamber, having an open bottom, a closed top and a spaced conical cap, being centrally located in the barn and space-dly supported above the floor of the barn. The combustion chamber is provided with heat ducts connected to its upper portion which extend radially outward therefrom to distribute heat to the outer portions of the barn away from the combustion chamber. A rectangular nonrotatable gas-manifold is connected to the lower portion of the combustion chamber and supported thereby. A gas burner and pilot light are supportedly maintained on the upper surface of this gas manifold in a vertically upstanding position. The system further includes a thermocouple controlled, solenoid operated, control valve connected to the gas manifold and a solenoid operated, thermocouple controlled, safety valve connected to the gas manifold which is capable of shutting-off the entire gas supply to the gas burner and pilot light.

This invention pertains generally to the curing of tobacco, and more particularly relates to an improved system and apparatus for curing tobacco in tobacco barns.

A general object of this invention is to provide an improved tobacco curing system and apparatus which produces a more uniform and desirable curing of the tobacco, rendering the same more valuable.

Another general object of the subject invention is to provide improved means for heating the interior of a building such as a tobacco barn by the use of gas.

A further object of the instant invention is to provide an improved device for distributing heat uniformly throughout a tobacco curing barn.

Still another object of this invention is to provide an improved heating device for use in a tobacco curing barn which may be adjusted and arranged to suit a multiplicity of conditions, and is such that the heat generated thereby may be directed to any desired location within the tobacco barn.

Yet another object of this invention is to provide an improved gas manifold and gas burner arrangement within a gas fired tobacco curing system.

Still another object of the subject invention is to provide an improved control system for use with a gas-fired tobacco curing apparatus.

Still a further object of the invention isto provide an improved gas fired tobacco curing system having a failsafe safety mechanism within the gas supply line closely adjacent the gas burner.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of the tobacco curing system of this invention arranged and positioned within a tobacco curing barn;

FIG. 2 is an elevational view partially in section of the tobacco curing system of this invention;

"ice

FIG. 3 is a cross-sectional view taken along line 33 of FIG. 2;

FIG. 4 is an elevation view of the pilot light arrangement and a portion of the control system of the tobacco curing apparatus;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3;

FIG. 6 is a plan view obtained along line 66 of FIG. 2;

FIG. 7 is an elevational view obtained along line 77 of FIG. 6; and

FIG. 8 is a schematic diagram showing the gas supply and control system of the tobacco curing system of this invention.

Referring now more particularly to the drawings, and specifically to FIG. 1; the tobacco curing system of this invention is generally indicated by reference numeral 10 and is adapted to be placed in a tobacco curing barn, the same being generally indicated by reference numeral 12. The barn 12 is provided with four vertically upstanding side walls as at 14 and a roof 16 overlying and joining these four walls, the roof being broken away in this view such that the positioning of the tobacco curing system of this invention may be seen. The barn is also provided with a door 18 hingedly mounted along one of its vertical sides to permit ingress and egress into and out of the interior of the tobacco curing barn 12.

The tobacco curing system is gas fired through a supply line 20 from a suitable source of gas supply such as LPG (liquified petroleum gas) tank 22. The gas used to fire this system may be butane, propane or other suitable LPG gases, or if available natural gas may be used.

The tobacco curing apparatus 10 (see FIG. 2) comprises a hollow cylindrical housing or combustion chamber 24 having a closed top 26 and an open bottom 28. Combustion chamber 24 is adjustably supported off the floor of the tobacco curing barn by a series, three being used in the embodiment depicted, of adjustable legs 30 such that air may pass into the chamber 24 through its open bottom 28. The legs 30 are vertically supported in a base or foot member 32 and are adjustably connected to the sides of the combustion chamber adjacent its lower edge by means of a mounting bracket 34 and adjustable thumbscrew 36. Spacedly mounted over closed top 26 of the housing 24 is a conical shaped cap 38 which extends outward slightly beyond the upstanding walls of housing 24. The cap 38 is supported on the top 26 by means of a supporting post 40 welded to top 26 and a number of supporting or spacing members 42 adjacent the outer edge of top 26. The cap 38 remains cool during the curing of the tobacco such that should some of the tobacco hanging in the barn accidentally fall onto this cap it will not burn. In other words this conical cap 38 acts as a safety feature in this system to prevent the burning of any tobacco which may inadvertently fall thereon during the curing process.

Disposed within the upper portion of cylindrical housing 24 and extending radially outward therefrom are a number of heat openings or heat vents 44 provided to distribute the heat generated within the combustion chamber 24, being centrally located within the tobacco barn, to the other portions and outer corners of the tobacco barn removed from this centrally located combustion chamber 24. There are eight of these heat openings 44 provided in the embodiment of the invention shown but more or less may be provided depending on the size of the tobacco barn and the arrangement of the apparatus desired. The heating openings 44 are attached to the combustion chamber 24 by means of welded flanges 46. At tached to these heat openings 44 are larger heat ducts 48 which extend radially outward from the combustion chamber 24 towards the corners and sides of the tobacco barn (see FIG. 1). Theheat ducts 48 terminate in an elbow section 50 such that the heat passing through these ducts is directed downward towards the floor of the tobacco barn upon leaving the ducts. The elbow 50 of the duct terminates in a rectangular opening 52 surrounded by a rectangular plate member 54, which is provided with an adjustable leg 56, mounted thereto by means of a mounting bracket 58, to adjustably support the heat duct 48 and vary the height of rectangular plate member 54 above the floor of the tobacco barn. The inside diameter of heat duct 48 is somewhat greater than the outside diameter of heat vent 44 and may be easily slid over the same in the direction of arrow 47 as depicted in FIG. 2. The loose fit between vent 44 and duct 48 provides for the easy and ready vertically upward and downward adjustment of the outer end of duct 48 by the means of adjustable leg 56. By adjusting the outer ends of the heat ducts 44 upward or downward the amount of heat directed to any one area of the tobacco barn may be varied; by moving the outer end of a heat duct upward a greater volume of heat will pass therethrough, and similarly by lowering the same a lesser amount passes therethrough.

Attached to the combustion chamber 24 adjacent its lowermost edges and supported thereby is a gas manifold 60 and a gas burner arrangement 62. The gas manifold 60 is rectangular in shape and once attached to the combustion chamber 24 acts as a brace to strengthen the lower portion of the combustion chamber adjacent its open bottom 28. The attachment of the rectangular gas manifold 60 to the combustion chamber 24 is provided by L-shaped angle member 64 one side of which is attached to the gas manifold 60 and the other side or leg of which extends into an opening or socket 66 provided in the side wall of combustion chamber 24 adjacent its yowermost edge. The other end of the gas manifold 60 is attached to the combustion chamber by means of a vertically upstanding member 68 which is welded to this end of the gas manifold and a wing bolt 70 extending through a hole in the side of the combustion chamber 24 and extending into a threaded hole provided in upstanding member 68 (see FIG. 7). A rectangular opening 72 is provided in the wall of combustion chamber 24 extending upward from its lowermost edge to provide a passage through which this end of the rectangular gas manifold 60 may extend. To install the gas manifold 60 and burner assembly 62 Within the combustion chamber 24 the horizontally extending side or leg of angle member 64 is first inserted into socket or opening 66 and then the other end of gas manifold 60 carrying vertically upstanding member 68 is inserted into the rectangular opening 72 of the combustion chamber and the wing bolt 70 is placed through the hole in the side of the combustion chamber and guided into the threaded opening in member 68 such that the gas manifold and burner assembly becomes attached to and is supported by the combustion chamber 24, which itself is spacedly supported by the means of adjustable legs 30 off the floor of the tobacco barn. The rectangular shape of gas manifold 60 and the mounting means on each end thereof Provide for the easy and ready attachment of the same to the combustion chamber 24 such that manifold 60 is supported by chamber 24 and becomes a bracing member thereof. Once manifold 60 is mounted within and becomes a part of chamber 24 it is non-rotatable and allows for the loose but safe vertical mounting of burner assembly 62 on its upper surface.

The gas burner assembly 62 as depicted in FIG. 3 rests loosely on and is supported by rectangular gas manifold 60 to which there is welded a circular supporting member 74. The main gas burner 76 easily slides into and out of circular supporting member 74 and rests on and is supported by rectangular gas manifold 60 and the sides of; supporting member 74. The gas, in traveling towards burner 76, through gas manifold 60 and orifice 78 contained within fitting 80, draws with it air through openings 82 between the bottom of burner 76 and manifold 60 (see FIG. 5), pulling the same through the open bottom 28 of combustion chamber 24. The gas and air mixture moves upward within burner 76 to the top portion thereof and when ignited results in a hot flame 84. Supported over the upper end of burner 76 is a flame spreader 86 provided to spread the flame 84 outward and sideward rather than having the same rise vertically upward to a great height. Flame spreader 86 is supported on a cylindrical shaft 88 extending upward into the vertical center opening 90 within the flame spreader. Shaft 88 which extends centrally upward from within burner 76 is connected to a cross-member 92, which in turn is attached to the sides of the burner 76. The upper portion 94 of the burner 76 is slightly enlarged such that the cross-sectional area of upper portion 94 which contains cross-member 92 and vertically upstanding cylindrical shaft 88 is equal to the cross-sectional area of the main portion of the burner 76, such that the flow of air and gas through these two portions 76 and 94 is equal.

Attached to supporting member 74 is a right angle member or bracket 96 to which is mounted the pilot light assembly 98. The lower portion of this pilot light arrangement 98 comprises a cross-shaped member 100 (see FIGS. 3 and 4) which has a T-shaped passage 102 therethrough and is mounted to bracket 96 by the means of a threaded bolt 104. One arm of the T-shaped passage 102 of member 100 is plugged by a threaded bolt 106 while the other arm is connected at 108 to the source of gas supply for the pilot light coming through pilot light flowline or tubing 110. The upstanding leg of T-shaped passage 102 leads to the pilot light gas orifice 112. Supported on the upper portion of cross-shaped member 100 is the pilot light burner 114 the upper end 116 of which is pinched or flattened to restrict the amount of gas and air mixture flowing therethrough and to spread the pilot gas flame 118. Two small holes 120 are provided in the sides of pilot light burner 114 adjacent its lower end such that air may be drawn therethrough to mix with the gas coming from orifice 112, which mixture passes upward through the interior of pilot light burner 114 and results in the pilot light flame 118 when ignited. Additionally two small holes 122 are provided in the sides of the pilot light burner 114 adjacent its upper end such that small portions 124 of the pilot light flame 118 extend outward through and upward from these holes 122 when the mixture of gas and air is ignited as depicted in FIG. 4. Connected to pilot light burner 114 at its mid-section is a mounting member 126 through and to which the e is mounted a 30 millivolt thermocouple 128 having an electrical connection 129 leading therefrom and a 700 m'illivolt thermocouple 130 with an electrical connection 131 leading therefrom, the function of these thermocouples to be explained hereinafter. The arrangement of the pilot light burner 114 and thermocouples 128 and 130 is such that when the pilot light flame 118 is burning its smaller portions 124 heat the upper portion of these thermocouples.

As previously explained, the source of gas supply to the main burner 76 comes from gas tank 22 through gas fiow line 20 as diagrammatically and schematically set forth in FIG. 8. In its travel through flow line 20 from the gas tank 22 to the burner 76 the liquified petroleum gas first passes through a variable regulator 132 which is normally set to deliver the gas on its downstream side at a pressure of from about 3 to 12 p.s.i.g. After leaving the regulator 132 at a reduced pressure the gas passes downward through flow line 20 to a hand operated mechanical valve 134 which is normally in the open position, but which may be closed to prevent any gas from flowing past this point within supply line 20. A pressure gauge 136 is normally provided closely adjacent the regulator 132 such that the pressure of the gas flowing to the tobacco curing apparatus may be periodically checked and the regulator adjusted if necessary. The gas supply tank 22 is normally spaced a good distance from the tobacco curing barn, that being usually 20 feet or more, as a safety precaution in case of fire in the barn to avoid the possibility of an explosion. Variable regulator 132 and valve 134 are normally positioned closely adjacent the gas supply tank 22 spaced outward from the tobacco curing barn 12. After leaving valve 134 the gas continues to flow down line 20 to a safety valve 138, which is solenoid operated and spring-biased to the closed position. This safety valve 138 will normally be in the opened position allowing gas to pass therethrough when its solenoid member 140 is energized such as to operate the valve to its open position. The solenoid 140 will be energized and safety valve 138 will be in the opened position to allow gas to pass therethrough when a voltage is produced in the thermocouple 128; this occurring when pilot light burner 114 is ignited to produce pilot light flames 118 and 124 such that the thermocouple 128 is heated. Next, continuing down the flow line 20 towards the main burner 76, the gas comes to a main control valve 142 which is also solenoid operated by solenoid member 146 and spring-biased to the closed position. Main control valve 142 will normally operate between its open and closed positions, depending on the temperature within the tobacco barn and the temperature desired to be maintained therein. If the main valve 142 is opened the gas passes therethrough to main burner 76 and is ignited by pilot light flame 118 resulting in the main gas flame 84 within the combustion chamber 24. The safety valve 138 and the main control valve 142 are positioned closely adjacent gas manifold 60 and combustion chamber 24 such that the gas supply may be controlled close to the gas burner and for other safety reasons.

Leading from one side of safety valve 138 and communicating and connecting with the lower end of pilot light burner 114 is the pilot light gas supply line 110. When the safety valve 138 is in the opened position gas will flow down this supply line 110 to the pilot light burner 114 and when ignited result in pilot light flames 118 and 124; but should the safety valve 138 be in the closed position gas will not flow through pilot light supply tube 110 nor through the remainder of gas flow line 20 leading to the main burner 76. When the pilot light burner 114 is ignited to result in pilot light flames 118 and 124 the small (30 millivolt) thermocouple 128 produces a suflicient voltage which is carried through its electrical leads 129 to energize and actuate solenoid 140 which operates to open safety valve 138. Should the flames 124 and 118 of the pilot light burner 114 for some reason or other be extinguished, thermocouple 128 will not produce a voltage to actuate solenoid 140 and safety valve 138 will be biased by its spring to the closed position such that all gas flow past the safety valve 138 is terminated. Safety valve 138 is provided with a finger operable lever 144 on its underside such that the valve 138 may be manually opened by an attendant or operator to permit gas to flow through the pilot light flow line 110 to the pilot light burner 114 and there ignited by match, torch or other suitable means to relight the system after a shutdown or failure of the same. After the pilot light is ignited and the thermocouple 128 is heated to produce enough voltage to energize and actuate solenoid 140, such that safety valve 138 will remain open, the operator may release lever 144.

Connected in series to solenoid 146 of main control valve 142 is the larger (700 millivolt) thermocouple 130, a safety limit switch 148 of the bimetallic type, and a variable thermostat 150 of the pressure-diaphragm type. The large thermocouple 130 produces when heated suflicient voltage which is conducted through its electrical leads 131 to energize and actuate solenoid 146 of the main control valve 142 such as to operate this valve to its opened position, provided the remainder of the large thermocouple circuit 131 is closed, which permits gas to flow through valve 142 and flow line 20 to the main burner 76, thereby to be ignited by pilot light flame 118 and produce the main gas flame 84. Should for one reason or another pilot light flames 118 and 124 be extinguished, the thermocouple will not produce the voltage necessary to energize solenoid 146 of the main control valve 142, even though the remainder of this thermocouple circuit 131 is closed and valve 142 will remain spring-biased in its closed position.

As previously stated, there is also contained in the circuit 131 of the larger thermocouple 130 safety limit switch 148, which switch is connected in series in the circuit and is of a bimetallic type. Safety switch 148 is positioned Within the tobacco curing barn such as to be exposed to and reflect the temperature within the barn. Under normal procedures the safety limit switch 148 is constructed such that it Will be actuated and operate to open this circuit should the temperature in the barn reach 190 F. If such a high temperature is reached, safety limit switch 148 operates to open the circuit 131, voltage will not be provided to solenoid 146, and the main valve 142 will be spring biased to its closed position, thus stopping the flow of gas to the main burner 76 and extinguishing main gas flame 84, whereby the temperature Within the tobacco barn will drop to a safer point somewhere below 190 F.

Additionally contained in series within circuit 131 of larger thermocouple 130 is variable thermostat 150, which is of the pressure-diaphragm type. Variable thermostat 150 is mounted on the outside of the tobacco barn 12 adjacent the door 18 and is provided with settings from approximately 90 to F. to provide for the range of temperatures desired in the curing of the tobacco. This thermostat 150 has a sensing bulb or element 152 which is positioned within the tobacco barn to measure and reflect, back through the barn wall 14 to the thermostat 150, the temperature within the tobacco curing barn. When the temperature within the tobacco curing barn falls below the setting of the thermostat 150 circuit 131 of thermocouple 130 will be closed such that solenoid 146 will be activated to operate valve 142 such that gas may flow to the main burner 76 and result in the main gas flame 84 being ignited by the pilot light flame 118, such that the temperature within the tobacco curing barn rises to the setting of the thermostat 150. When this temperature setting is reached Within the barn, contact will be broken, at the thermostat opening circuit 131 of thermocouple 130 such that solenoid 146 is deenergized and valve 142 is spring biased to its closed position, thus extinguishing gas flame 84 of main burner 76 whereby the temperature within the tobacco curing barn does not rise above the Setting on the thermostat 150.

To assemble and make operational the tobacco curing system and apparatus of this invention, the combustion chamber 24 is first centrally placed within the tobacco curing barn similar to that as shown in FIG. 1. The combustion chamber is supported by its adjustable legs 30 a distance, usually 8 inches in practice, above the floor of the tobacco barn. Next the heat ducts 48 are placed over and on the heat vent openings 44 by sliding the ducts 48 over the heat vents 44 in the direction of arrow 47 as depicted in FIG. 2. The outer ends 52 of these heat ducts 48 are supported by the adjustable wire leg 56 being mounted to the member 54 such that the height above the tobacco barn floor of these ends 52 may be varied to either increase or decrease the amount of heat ducted to any given area within the barn. The connection of duct 48 and heat vent 44 is quite loose such that the outer end 52 of the duct may be easily moved in a vertical direction upward or downward. Once the heating ducts 48 are in place, the rectangular gas manifold 60 supporting and carrying burner assembly 62 is mounted to the combustion chamber 24 adjacent its lower edge by inserting the horizontal leg of member 64 into its socket 66 in the side of the combustion chamber and inserting wing bolt 70 through the hole in the wall on the opposite side of the combustion chamber and threading the same into the threaded opening provided within vertically upstanding member 68 on the manifold 60, thereby securing manifold 60 in place such as to further brace combustion chamber 24. As a final step, gas supply line is connected to the gas tank 22 which is spacedly removed from the tobacco barn, usually at least 20 feet. and the source of the liquified petroleum gas contained therein, to make the system operational.

In the operation of the tobacco curing system of this invention, the barn will first be filled with the tobacco to be cured, hanging the same from the rafters within the barn above the curing apparatus 10. Once the barn has been filled with tobacco the attendant or operator will open valve 134 to permit the gas within tank 22 to flow to safety valve 138, where the attendant or operator by depressing lever 144 within this valve permits gas to flow through pilot light supply line 110 to the pilot light burner 114 and ignites the same to produce pilot light flames 118 and 124. When the pilot light flame has sufficiently heated small thermocouple 128 such that solenoid 140 is energized and operates to maintain safety valve 138 in its open position, the attendant may release the previously depressed lever 144 of safety valve 138. The pilot light, of this system, in and of itself, is normally sufficiently large, depending of course on the size of the barn, to act as the coloring burner to initially cure or color the tobacco hanging within the curing barn. The coloring usually takes place at temperatures of from 90 to 100 R, which may be controlled by variable thermostat 150, under conditions of high humidity, which are provided by closing all vents of the barn, and for periods of approximately one or two days. After this initial curing or coloring has taken place, the variable thermostat 150 is increased to a temperature of approximately 140 to 160 F. and all vents of the barn are opened both in the top and bottom thereof until the leaves are dry, which process usually takes in the neighborhood of two days. During this drying process the main gas burner 76 will of course periodically be supplied with gas through flow line 20, resulting in main gas flame 84, the same being ignited by pilot light flame 118, when the main control valve 142 periodically opens and closes. The opening and closing of the main control valve 142 being controlled by the making and breaking of circuit 131 of thermocouple 130 at the variable thermostat 150 depending on the setting of the same and the temperature within the tobacco barn. The barn is heated by circulating warm air therein, the cooler air first being drawn from adjacent the barn floor through the open bottom 28 of the combustion chamber 24 (see FIG. 2) and heated at the burner assembly 62 by the hot gas flame 84. This then heated air moves upward within the combustion chamber 24 in the direction of arrows 43 and outward through the heat ducts 48 in the direction of arrows 45 to circulate warm air and heat to those portions of the barn spaced outward of the combustion chamber. After the drying process the barn is again completely closed and the variable thermostat 150 is set at temperatures in the range of 160 to 170 F. for a period of eight to twelve hours to thoroughly dry the stems of the tobacco leaves, after which the now fully cured tobacco is removed from the barn and made ready for market.

While only a certain preferred embodiment of this invention has been shown and described by way of illustration, many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended in the appended claims to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. In a gas-fired tobacco curing system for curing tobacco hung in a barn, comprising a combustion chamher centrally located within the barn, first adjustable means for spacedly supporting said chamber above the floor of the barn, said combustion chamber having heat ducts extending radially outward from its upper portion to distribute heat to the outer portions of the barn away from said combustion chamber, means movably mounting said heat ducts to said combustion chamber, and second adjustable means for supporting the outer ends of said heat ducts at selective heights above the fioor of the barn thereby to control the amount of heat distributed to any given area within the barn.

2. In a gas-fired tobacco curing system for curing tobacco hung in a barn having a cylindrical combustion chamber centrally located within the barn and spacedly supported above the floor of the barn, said combustion chamber having heat ducts connected to its upper portion and extending radially outward therefrom to distribute heat to the outer portions of the barn away from said combustion chamber, the improvement comprising a rectangular gas manifold extending diametrically across the lower portion of said combustion chamber and supported thereby, a rectangular socket located in one side of said combustion chamber for connectively receiving one end portion of said rectangular manifold, the opposite side of said combustion chamber having a slot therethrough oppositely disposed from said socket for receiving the other end portion of said rectangular manifold therethrough, said slot generally conforming to the cross-section of said manifold and partially surrounding the same to prevent rotation of said manifold within said slot, an upstanding member having a threaded opening therein attached to said manifold closely adjacent said manifolds other end and a thumbscrew extending through an opening in said combustion chamber adjacent said slot and into said threaded opening in said upstanding member thereby to securely connect said rectangular manifold to said combustion chamber.

3. In the gas-fired tobacco curing system of claim 2, wherein the combustion chamber has an open bottom and closed top, a conical cap-like member which extends outward of the cylindrical side of said combustion chamber, and means for connecting said member to and spacedly supporting the same above said closed top of said combustion chamber to provide an air space therebetween, said member being maintained relatively cool with respect to said combustion chamber during operation thereof whereby tobacco inadvertently falling thereon is not ignited.

4. The gas-fired tobacco curing system as defined in claim 2, furthe comprising a gas burner, a member connected to said manifold for maintaining and supporting said burner in a vertically upstanding position, said manifold being maintained with the upper manifold surface generally horizontal and said burner resting thereon and extending vertically upward therefrom, whereby the gas flame of said gas burner is directed and maintained vertically upward within said combustion chamber.

5. In a gas-fired tobacco curing system for curing tobacco hung in a barn having a combustion chamber and a gas manifold connected to and extending across the lower portion of said combustion chamber, the improvement comprising a normally closed solenoid operated safety valve connected to said manifold closely adjacent and exteriorly of said combusition chamber, a thermocouple connected in circuit to the solenoid of said valve and positioned interiorly of said combustion chamber, a pilot light in said combustion chamber adapted and arranged to ignite the gas in the combustion chamber when gas is being passed through said manifold, said pilot light being operative to heat said thermocouple and produce a voltage which activates said solenoid of said safety valve to maintain said valve open, said valve being closed to shut off the entire gas flow when the voltage produced byhsaid thermocouple ceases upon failure of said pilot lig t.

6. A gas-fired tobacco curing system for curing tobacco hung in a barn comprising a combustion chamber, a gas manifold extending across the lower portion of said combustion chamber and attached thereto, a gas burner and pilot light therefor positioned within said combustion chamber, a source of gas supply connected to said manifold outwardly of said combustion chamber, a solenoid operated control valve being spring-biased to the closed position connected to said manifold closely adjacent and outward of said combustion chamber to control the flow of gas from said supply through said manifold to said gas burner, a thermocouple positioned within said combustion chamber closely adjacent said pilot light and connected in circuit to the solenoid of said control valve so as to produce a voltage in said solenoid to operatively open said control valve when said pilot light sufliciently heats said thermocouple, an upper limit safety thermostat positioned exteriorly of said combustion chamber and connected in circuit to said solenoid of said control valve, and an adjustable thermostat positioned exteriorly of said combustion chamber and connected in circuit to said solenoid of said control valve to regulate the temperature maintained within the barn.

7. The gas-fired tobacco curing system as defined in claim 6, further comprising a solenoid operated safety valve being spring-biased to the closed position connected to said manifold adjacent and outward of said combustion chamber, and an additional thermocouple positioned within said combustion chamber closely adjacent said pilot light and connected in circuit to the solenoid of said safety valve so as to produce a voltage in said solenoid to operatively open said safety valve when said additional thermocouple is sufiiciently heated by said pilot light, said safety valve being closed to shut off the entire gas supply to said gas burner and pilot light when the voltage produced by said additional thermocouple ceases upon failure of said pilot light.

References Cited UNITED STATES PATENTS 2,533,092 12/1950 Chestnutt 263-19 2,783,988 3/1957 Garner 263-19 2,943,850 7/1960 Moseley 263-19 3,007,689 11/1961 Mayo 263-19 FREDERICK L. MATTESON, JR., Primary Examiner. JOHN J. CAMBY, Examiner. 

